There are a considerable number of golf aids which have been developed over the years with the general object to train a golfer to improve his golf swing. Such golf training devices have variously sought to teach improved golf swings by restraining torso movements, hip movements, shoulder movements, arm movements, and head movements. For example, U.S. Pat. Nos. 2,626,151; 3,415,523; and 3,698,721 show elaborate golf training devices having mechanisms for controlling the movement of the user's head.
I have made a study of the geometric elements of the golf swing including the user's body axis, the torso axis, and the inclinations of each of these axes with the ground. The body axis extends from the top of the head through a point midway between the outer surfaces of the eyes to a point on the ground midway between the balls of the feet. I have found that to make the best possible golf swing the length of this axis and its inclination with the ground should remain relatively unchanged throughout both the back swing and the down swing. The difficulty in doing just this can, of course, be observed in practice, often with the reiterated reminder "to keep the head down." Common errors which occur in making the swing include pulling up on the back swing and straightening up on the down swing.
When the body axis is viewed from the side, it may be seen that the only hip movement that will not result in lengthening or shortening of the body axis is a swing of the hips around the body axis. That is, by keeping the radius from the body axis to the hips relatively unchanged throughout the swing. Also, the body axis must not be lengthened or shortened by inclining or declining the head from its inclination at the address of the ball, or by moving the head forward or backward, side-to-side, or causing it to move up or down by changing the inclination of the torso axis.
The torso axis extends generally from around the top of the head to midway between the hip sockets. The respective rotations of the club, arms, shoulders and the torso around the torso axis provide the leverage to produce power for the swing. As the hips rotate, the lower end of the torso axis rotates around the body axis.
The torso axis and the body axis intersect at about the top of the head. I have found that movements around these two axes are to be managed and coordinated to keep the point of their intersection fixed as nearly as possible to thereby improve the golf swing. That is, an improved golf swing results where the inclination of the torso axis with the body axis remains unchanged during the swing, and the intersection point of the two axes remains substantially fixed from address through the conclusion of the swing. Keeping the point of intersection at the top of the head fixed excludes movement of the head up or down, left or right, and front or back during the swing. The head may however rotate around the torso axis and swing around the body axis. Sufficient rotation of the head around the torso axis is desirable to smoothly blend head and body movements. A better golf swing is also accomplished where rotations around the body and torso axes are as simple as possible, i.e., with little or no motion except rotary motion.
It is thus among the principal objects of this invention to provide a golf training device to maintain fixed the intersection of the user's torso axis with the user's body axis during a golf swing to thereby produce a better swing.
A further object of the invention is to provide such a device for maintaining fixed the intersection of the torso and body axes through the use of a mechanism which substantially constrains movement of the user's head to rotation about the torso axis and about the body axis, with only limited head movement along the body axis otherwise being permitted.